Midrash su Levitico 21:3

11) (Vayikra 21:3) ("And for his sister, the virgin, who is near to him, who was not wed to a man — for her shall he make himself tamei.") "and for his sister, the virgin": to exclude one who was forced or seduced. I might think that I (also) exclude one whose hymen was accidentally ruptured. It is, therefore, written "who was not wed to a man," (the implication being) one who lost her virginity by being possessed by a man, and not through other causes.

12) "who is near": to include one who was betrothed. "to him": to include a bogereth (one beyond the age of twelve and a half, even if she lost part of her virginal signs in the process of maturing). "for her shall he make himself tamei": It is a mitzvah to do so. If he demurred, we force him to do so. And it happened with Yosef the Cohen, whose wife died on the eve of Pesach, and who did not wish to make himself tamei for her, that the sages pushed him and made him do so perforce.

13) "for him shall he make himself tamei": for (one who is his sister of) a certainty; and he does not make himself tamei for one who is not his sister or a certainty. "for her shall he make himself tamei": and not for others with her, i.e., he should not say: Since I have already made myself tamei (for her), I shall collect the bones of so and so. "for him shall he make himself tamei": but not for her (discrete) limbs, which she lost when she was alive, his being forbidden to do so (even) for the limbs of his father; but he does make himself tamei for a bone the size of a barley-corn of his father.